1. Field of the Invention
The present invention generally relates to a method and apparatus for providing wireless data service, and more particularly to a method and apparatus for setting up a Point-to-Point Protocol (PPP) link between a Terminal Equipment (TE) and a Mobile Terminal (MT), and between the MT and a Base Station (BS) Interworking Function (IWF).
2. Description of the Related Art
Generally, in wireless data communication using a Personal Computer (PC), devices making communication perform a subscriber authentication between them using PPP, and are assigned with Internet Protocol (IP) addresses. The PPP is a scheme widely used for access to the Internet, and is defined as a standard in RFC (Request For Comment) 1661 and RFC 1162, to which reference will be made in the following description.
FIG. 1 shows a protocol stack of each entity in a typical wireless communication system. A Terminal Equipment (TE2) 101 is directly connected to a Mobile Terminal (MT2) 102 over a serial interface (I/F) 114 of an Rm communication scheme, in which the connection is achieved by a medium including, for example, an RS-232, a Universal Serial Bus (USB), and/or other wired/wireless interfaces. The MT2 102 communicates wirelessly with an IWF 104 through a BS 103.
In FIG. 1, the TE2 101 includes a mobile terminal, a laptop computer, a palmtop computer, or the like, and the MT2 102 includes devices, such as a Personal Digital Assistant (PDA) portable telephone, etc., capable of performing data communication through wireless access to the BS 103.
At the far left of FIG. 1 is a protocol stack depicting the protocol layers running on the TE2 101. The protocol stack of the TE2 101 is logically connected to a protocol stack of the MT2 102 over an Rm interface 150. The protocol stack of the MT2 102 is connected to a protocol stack of the BS 103 over a Um interface 160. The protocol stack of the BS 103 is logically connected to a protocol stack of the IWF 104 over an L interface 170.
The protocol stacks will now be described.
A Radio Link Protocol (RLP) 126 and an Interim Standard 95 (IS-95) protocol 127 are standards defined to transfer upper data in Code Division Multiple Access (CDMA) mobile communication. In uplink data communication from the TE2 101, packets generated in an upper layer 111 are transferred through a network layer 112 to a PPP-R layer 113, and then are framed into PPP frames in the PPP-R layer 113.
The generated PPP frames are transferred to the MT2 102 through the serial interface 114. The MT2 102 unframes the PPP frames received through a serial interface 124 in a PPP-R layer 123, and again generates PPP frames to be transmitted to the IWF 104. This is because it is necessary to reconstruct frames depending on negotiated PPP link options on the Um interface. That is, the PPP-R layer 123 transfers the unframed packets to a PPP-U layer 125, and the PPP-U layer 125 frames the packets into PPP frames to be transmitted to a PPP peer in which the IWF 104 is located.
The PPP-R layer 113 of the TE2 101 and the PPP-R layer 123 of the MT2 102 negotiate Link Control Protocol (LCP) options to configure the Rm interface 150.
The RLP 126 and the IS-95 protocol 127, both of which are well known in the art, are used to transmit packets encapsulated in PPP frames to the BS 103 over the Um interface 160. An RLP layer 128 and an IS-95 layer 129 of the BS 103 transfers the packets to a relay layer 130 of the BS 103 to transmit the packets to a relay layer 149 of the IWF 104 over the L interface 170. The relay layer 149 of the IWF 104 transfers the packets received from the relay layer 130 of the BS 103 to upper layers 145, 142 and 141 in the IWF 104.
Thereafter, PPP frames are transferred to the IWF 104 through the BS 103, the PPP-U layer 145 unframes received packets, and the network layer 142 packets received from the PPP-U layer 145 to the upper layer 141. Even in the case of downlink data communication, the aforementioned uplink data communication procedure is identically applied according to the reverse order of the procedure.
As described above in connection with the prior art, since links in which a plurality of PPP sessions have been negotiated have different characteristics, it is necessary to perform an unframing (decapsulating) process and a framing (encapsulating) process in order to relay frames, thereby increasing the processing load on a processor, so that a restriction occurs in performance for data communication which is progressing toward faster service. International Publication Number WO 01/05177 A1, published on Jan. 18, 2001, discloses a method which causes each of the PPP-R layer 123 and PPP-U layer 124 to have a default option, to determine whether finally negotiated options are the same, and to omit the unframing and framing processes only when the finally negotiated options are the same.
However, the conventional method described above has a disadvantage in that when an option finally negotiated between the PPP-R layer, which negotiates option values between the Rm interfaces, and the PPP-U layer, which negotiates option values between the Um interfaces, has a value other than the default value defined in the specification, the method cannot be applied. That is, the above-described conventional method can be applied only when option values for configuring an LCP have been negotiated to an initial default value at both of Rm interface and Um interface, so the application range of the method is greatly restricted.